Are surface temperature records reliable?
Select a level... Basic Intermediate Advanced
The warming trend is the same in rural and urban areas, measured by thermometers and satellites, and by natural thermometers.
"We found [U.S. weather] stations located next to the exhaust fans of air conditioning units, surrounded by asphalt parking lots and roads, on blistering-hot rooftops, and near sidewalks and buildings that absorb and radiate heat. We found 68 stations located at wastewater treatment plants, where the process of waste digestion causes temperatures to be higher than in surrounding areas.
In fact, we found that 89 percent of the stations – nearly 9 of every 10 – fail to meet the National Weather Service's own siting requirements that stations must be 30 meters (about 100 feet) or more away from an artificial heating or radiating/reflecting heat source." (Watts 2009)
Temperature data is essential for predicting the weather. So, the U.S. National Weather Service, and every other weather service around the world, wants temperatures to be measured as accurately as possible.
To understand climate change we also need to be sure we can trust historical measurements. A group called the International Surface Temperature Initiative is dedicated to making global land temperature data available in a transparent manner.
Surface temperature measurements are collected from about 30,000 stations around the world (Rennie et al. 2014). About 7000 of these have long, consistent monthly records (Fig. 1). As technology gets better, stations are updated with newer equipment. When equipment is updated or stations are moved, the new data is compared to the old record to be sure measurements are consistent over time.
Figure 1. Station locations with at least 1 month of data in the monthly Global Historical Climatology Network (GHCN-M). This set of 7280 stations are used in the global land surface databank. (Rennie et al. 2014)
In 2009 some people worried that weather stations placed in poor locations could make the temperature record unreliable. Scientists at the National Climatic Data Center took those critics seriously and did a careful study of the possible problem. Their article "On the reliability of the U.S. surface temperature record" (Menne et al. 2010) had a surprising conclusion. The temperatures from stations that critics claimed were "poorly sited" actually showed slightly cooler maximum daily temperatures compared to the average.
In 2010 Dr. Richard Muller criticized the "hockey stick" graph and decided to do his own temperature analysis. He organized a group called Berkeley Earth to do an independent study of the temperature record. They specifically wanted to answer the question is "the temperature rise on land improperly affected by the four key biases (station quality, homogenization, urban heat island, and station selection)?" Their conclusion was NO. None of those factors bias the temperature record. The Berkeley conclusions about the urban heat effect were nicely explained by Andy Skuce in an SkS post in 2011. Figure 2 shows that the U.S. network does not show differences between rural and urban sites.
Figure 2. Comparison of spatially gridded minimum temperatures for U.S. Historical Climatology Network (USHCN) data adjusted for time-of-day (TOB) only, and selected for rural or urban neighborhoods after homogenization to remove biases. (Hausfather et al. 2013)
Temperatures measured on land are only one part of understanding the climate. We track many indicators of climate change to get the big picture. All indicators point to the same conclusion: the global temperature is increasing.
Understanding adjustments to temperature data, Zeke Hausfather
Explainer: How data adjustments affect global temperature records, Zeke Hausfather
Time-of-observation Bias, John Hartz
Berkeley Earth Surface Temperature Study: "The effect of urban heating on the global trends is nearly negligible," Andy Skuce
Check original data
All the Berkeley Earth data and analyses are available online at http://berkeleyearth.org/data/.
Plot your own temperature trends with Kevin's calculator.
Or plot the differences with rural, urban, or selected regions with another calculator by Kevin.
NASA GISS Surface Temperature Analysis (GISSTEMP) describes how NASA handles the urban heat effect and links to current data.
NOAA Global Historical Climate Network (GHCN) Daily. GHCN-Daily contains records from over 100,000 stations in 180 countries and territories.
Last updated on 15 August 2017 by Sarah. View Archives
It's Urban Heat Island effect
1934 - hottest year on record
A good introduction to the history and analysis of surface temperature measurements is "Tales from the Thermometer" by Tamino.
"Surface Stations" by Tamino examines the two "poster stations" on the homepage of surfacestations.org, having a close look at the actual data from both stations.
The adjustments NASA makes are fully documented and available online. Tamino explains it in a more digestible format in "Best Estimates".
To understand what exactly happened with NASA's USA temperature glitch, check out James Hansen's explanation "A Light On Upstairs" and a follow-up "The Real Deal: Usufruct & the Gorilla". You can read Steve McIntyre's reply here.
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Comments 501 to 519 out of 519:
MA Rodger at 02:18 AM on 26 September, 2017
randman @497.
♣ You ask "how do we know?" If you examine the LOTI documentation (linked @496) you will see it says "GLOBAL Land-Ocean Temperature Index in 0.01 degrees Celsius - base period: 1951-1980" And while it is fuzzed out past p1, Hansen & Lebedeff (1988) is but an update of Hansen & Lebedeff (1987) and that states "We obtain monthly temperature changes for a given subbox by applying the previously described procedure individually to each of the 12 months, with the zero point for each month being its 1951-1980 mean." So unless there is some ambiguity over the year numbering, it all sounds pretty "knowable".
♣ You ask "what is that base specifically in abolute temps?" I would quote you the comment from 1988 quoted in one of those NYT articles you have cited up-thread.
"How hot is the world now? The scientists do not offer a straightforward response, saying that the vast amount of data is still being studied and that comparisons cannot be precise."
If you insist on a reply, perhaps this NASA article will provide it. It states "For the global mean, the most trusted models produce a value of roughly 14°C, i.e. 57.2°F, but it may easily be anywhere between 56 and 58°F."
This of course is neither an exact answer nor the 59°F/15°C you have cited from a couple of NYT articles, but as I set out @478 above, the NYT 59°F value is almost certainly the result of the journalist (it is each time the same journalist) insisting on using an absolute temperature and effectively putting words into a climatologists mouth, words they do not object to. But it ain't science.
The Ts=288K you also cite (from Hansen et al 1981) is not applicable to any anomaly base. It is used for the same perpose that Callendar (1938) uses Ts=283k, to quantify the magnitude of the greenhouse effect. It has no association with any defined time-period.
♣ You state 1988 was "Same year he testified that the 1950-1980 mean was 59 degrees F." This I assume refers to Hansen's tesemony to US Senate Committee on Energy & Natural Resources 23/6/1988. This is not something I am familiar with but if Hansen does testify "that the 1950-1980 mean was 59 degrees F," it will require sharper eyes than mine to see it. Perhaps you can point to the page & paragraph.
♣ You will note that Hansen & Lebedeff (1987) tabulates the global anomaly record 1880-1985. I cut&pasted those numbers into a spreadsheet alongside todays GISTEMP LOTI 1880-2016. The resulting graph can be see here (usually 2 clicks to 'download your attachment'). There is significant difference between the 1980s record and today's but only pre-1940.
(Folk get obsessed with the impact such adjustments would have on the implied global warming by popping a LSR through the data. Such analysis 1880-1985 shows the 1980s data implies there has been a little more warming over the period than shown in the modern data, 0.54°C/century as opposed to 0.44°C/century.)
randman at 02:19 AM on 26 September, 2017
" If there were no greenhouse effect, the Earth's average surface temperature would be a very chilly -18°C (0°F) instead of the comfortable 15°C (59°F) that it is today."
https://earthobservatory.nasa.gov/Features/GlobalWarming/page2.php
This was put out in 2010. There is an accompanying graph showing a significant rise from 1980 and the the period of 1950-1980 along with this comment:
"By the beginning of the 21st century, Earth's temperature was roughly 0.5 degrees Celsius above the long-term (1951–1980) average. (NASA figure adapted from Goddard Institute for Space Studies"
So we see a mean mentioned in 2010 of "15°C (59°F) that it is today."
This is said to be roughly .5 Celsius above the 1950-1980 mean, which would make the 1950-1980 mean be 58.1 degrees F. As I have shown in other posts, the mean was reported to be 59 degrees in 1988. Obviously, it was adjusted downward.
"One of the scientists, Dr. James E. Hansen of the National Aeronautics and Space Administration's Institute for Space Studies in Manhattan, said he used the 30-year period 1950-1980, when the average global temperature was 59 degrees Fahrenheit, as a base to determine temperature variations."
http://www.nytimes.com/1988/03/29/science/temperature-for-world-rises-sharply-in-the-1980-s.html
"Dr. Hansen informed the lawmakers that the first five months of 1988 were the hottest five-month period on record, averaging four-tenths of a degree above a 30-year (1950-1980) norm of 59 degrees Fahrenheit."
"The British readings showed that the average global temperature in 1988 was 0.612 degrees Fahrenheit higher than the long-term average for the period 1950 through 1979, which is a base for comparing global temperatures. The average worldwide temperature for that 30-year period is roughly 59 degrees Fahrenheit, the British researchers said."
http://www.nytimes.com/1989/02/04/us/global-warmth-in-88-is-found-to-set-a-record.html
And from 1991:
"The Goddard group found that the record average surface temperature for the globe was eight-tenths of a degree Fahrenheit above the 1951-1980 average of 59 degrees. The British group found it seventh-tenths of a degree higher than the 1951-80 average."
http://www.nytimes.com/1991/01/10/us/separate-studies-rank-90-as-world-s-warmest-year.html
Also note from the same article:
"The British groups, headed by Phil Jones at East Anglia and David Parker of the meteorological office, reported 1990 to be the warmest year since comparable records were first kept in 1850.....
The Goddard group found that the record average surface temperature for the globe was eight-tenths of a degree Fahrenheit above the 1951-1980 average of 59 degrees. The British group found it seventh-tenths of a degree higher than the 1951-80 average."
Looks like 59 degrees was considered the 1950-1980 mean in 1991, and in 2010 that was revised downward to 58 degrees.
So what is considered the 1950-1980 mean more recently? Here is an estimate and claim of 2015 being the hottest year.
"The NASA team found that globally averaged temperatures from January through December 2015 were 0.87 degrees Celsius (1.57° Fahrenheit) above the norm (defined as a 1951–1980 base period)."
https://earthobservatory.nasa.gov/IOTD/view.php?id=87359
If the mean was still 58 degrees, then 2015 would then have averaged nearly 60 degrees. 2016, however, is now considered the hottest year ever at less than 59 degrees.
"NOAA reported an average temperature for the year of 14.83 degrees C (58.69 degrees F) in 2016 – 1 degree C (1.69 degrees F) warmer than the average for the 20th century."
https://news.mongabay.com/2017/01/nasa-and-noaa-2016-hottest-recorded-year-ever/
[RH] Shortened link that was breaking page format.
Not sure how to edit a post. For 502, meant to write by 2010, the mean had been revised downward. Not sure when it happened, sometime between 1991 and 2010 it appears or perhaps it fluctuates?
MA Rodger, let's not miss the forest for the trees. I addressed some of this in another post.
If the mean was still 58 degrees, then 2015 would then have averaged nearly 59.57 degrees. 2016, however, is now considered the hottest year ever at less than 59 degrees.
[JH] You are comparing apples to oranges. The NASA computation of global mean surface temperature differs from that of NOAA's.
Ok, let's stick with NASA.
"They depict how much various regions of the world have warmed or cooled when compared with a base period of 1951-1980. (The global mean surface air temperature for that period was estimated to be 14°C (57°F), with an uncertainty of several tenths of a degree.)"
https://earthobservatory.nasa.gov/Features/WorldOfChange/decadaltemp.php
This appears to be from 2015 since the last year on the graph is 2014.
In 2010, we see 59 degrees given as the global mean at that time. The nature of the comment suggests to me 59 degrees is an approximate.
"the Earth's average surface temperature would be a very chilly -18°C (0°F) instead of the comfortable 15°C (59°F) that it is today."
Nasa reported 2010 as 1.13F degrees "warmer than the average global surface temperature from 1951 to 1980."
"The analysis found 2010 approximately 1.13°F warmer than the average global surface temperature from 1951 to 1980. "
https://www.giss.nasa.gov/research/news/20110112/
If the global mean from 1951-1980 were 57 degrees as they said it was in 2015, then 2010 would be 58.13 degrees, right?
But we just saw where they said it was approximately 59 degrees in 2010, not 58 degrees. Kind of a big deal.
Clearly, the baseline mean of 1950-1980 has not remained consistent in these calculations. Why?
[JH} See NASA's History of GISTEMP.
Note the reference to the mean as 59 degrees or 14.5 Celsius in 2009.
"Figure 1: The world's surface air temperature change ("anomaly"), relative to the world's mean temperature of 58° F or 14.5° C, averaged over land and oceans from 1975 to 20082."
https://www.nasa.gov/topics/earth/features/upsDownsGlobalWarming.html
[JH] In your first sentence, you incorrectly state "59 degrees". It should be "58 degrees".
Also note that the baseline period for Figure 1 is 1975 to 20082, not to 20082.
What relevance does this factoid have to your prior comments?
Meant to write 58 degrees. That was 2009. The reference to 1975 through 2008 refers to years on the graph, not the mean those years were compared to. That mean is 58 degrees, not the average of 1975-1982 as can easily be seen by viewing the graph.
This is relevant since we are discussing changes in the mean, the years 1950-1980.
Note just a few years later, probably 2015 as the data stops at year 2014, I believe:
""They depict how much various regions of the world have warmed or cooled when compared with a base period of 1951-1980. (The global mean surface air temperature for that period was estimated to be 14°C (57°F), with an uncertainty of several tenths of a degree.)"
So Nasa states here the "base period of 1950-1980" is estimated at 57 degrees, not 58 degrees.
[JH] The answer to your question can be found in NASA's posted Q&A, The Elusive Absolute Surface Air Temperature (SAT).
The Preface of his Q&A provides context:
The GISTEMP analysis concerns only temperature anomalies, not absolute temperature. Temperature anomalies are computed relative to the base period 1951-1980. The reason to work with anomalies, rather than absolute temperature is that absolute temperature varies markedly in short distances, while monthly or annual temperature anomalies are representative of a much larger region. Indeed, we have shown (Hansen and Lebedeff, 1987) that temperature anomalies are strongly correlated out to distances of the order of 1000 km.
The final Q&A of the post:
Q. What do I do if I need absolute SATs, not anomalies?
A. In 99.9% of the cases you'll find that anomalies are exactly what you need, not absolute temperatures. In the remaining cases, you have to pick one of the available climatologies and add the anomalies (with respect to the proper base period) to it. For the global mean, the most trusted models produce a value of roughly 14°C, i.e. 57.2°F, but it may easily be anywhere between 56 and 58°F and regionally, let alone locally, the situation is even worse.
My bold above.
randman at 13:29 PM on 26 September, 2017
To the mod:
Of course, but there still has to be some reason for the varying differences in the mean (1950-1980). What are those reasons?
Are they using different weather stations for one run and another?
Have they adjusted the past data? If so, why?
Is the algorythmn different?
A combination of these factors and others?
For some reason, there appear to be different means from a past time-frame and so anomalies are a separate topic. Sure, you calculate anomalies from each weather station or buoy but why then, if the same data points used, do you come up with a different mean over the past 30 years?
[TD] Read this then this then this. Then section 6 starting on page 190 of this.
[PS] No you dont get different means. That never changes. You are continuing to conflate "mean of baseline" with absolute temperature despite everyones efforts. What is so hard to understand about this?
And yes, they do adjust the data. Read the article. Do you seriously think you should not adjust data if say a screen is added over thermometer; the station is moved; or read at 3pm instead of 9pm? Even so, you can see that adjusted versus unadjusted data makes little difference. The biggest adjustment is to sea surface temperature and the adjustment reduces the trend not increases it. If science is some conspiracy to make you poor, why would they do that? Stop believing nonsense.
To the mod, read some of it. Will read more again later. Initial thoughts on this stuff is that the response to genuine questions appear to be "trust us", we know this and you do not. We can teach you, etc, etc,...and somewhat avoding the straightforward issue raised. I am not referring to you individually but rather the whole proponent industry.
The thing is every marker and everything many of us have learned about human behavior tells us, those on the fence or skeptics, that all of this has the hallmarks and "tell" of a sham. Now you can blast me, ban me or whatever. At this point I am not really trying to win an argument but just share how it comes off.
In fact, with the public, I think you guys have already lost but may not know it yet.
There are certain "tells" one learns to see in life. Over time, you see those patterns and learn. Of course you want to make sure, ask the right questions, hear the response and so forth. Be open-minded but the one thing you can't do is ignore the warning signs and there are a whole bunch of them here.
[PS] Obviously we cannot help the wilfully ignorant.
Eclectic at 16:15 PM on 26 September, 2017
Randman @509 , the objective evidence "tells" that you are talking rubbish.
Hard-core science-deniers such as you, will go to their graves before they will admit to the evidence in front of their eyes — though I suspect that some deniers will eventually back-pedal and try to re-write their history and will try to tell their grandchildren: "No, no, I was never one of those deniers — it's just that I had a few little doubts during the early stages of AGW".
MA Rodger at 17:43 PM on 26 September, 2017
You implore me not to "not miss the forest for the trees." Then you entirely dismiss my comments @501 saying "I addressed some of this in another post." It would be interesting to see if you could find that "other post" amongst this tangled comment thread you weave here. It is not evident to me.
Nobody can understand the "forest" without examining the "trees" and in your case you appear incapable of doing that.
Let us consider just one tree - the testimony of Hansen to the 1988 Senate Committee.
You have provided a newspaper articleof 5/7/88 which purports to inform their readers that Hansen told the Senate Committee about the 1951-80 anomaly base, that the average global temperature of that period was 59F. Yet have you ever heard the old adage "Don't believe everything you read in newspapers."? In this case it is good advice.
The newspaper quote looks quite definite. From The Day we read:-
All in black&white from a 1988 newspaper report. But for your purposes it isn't worth the paper it's written on! For a start, this is not what the NYT reported on the matter. From the NYT we read:-
"Dr. Hansen, who records temperatures from readings at monitoring stations around the world, had previously reported that four of the hottest years on record occurred in the 1980's. Compared with a 30-year base period from 1950 to 1980, when the global temperature averaged 59 degrees Fahrenheit, the temperature was one-third of a degree higher last year." (My bold)
And we also have the actual testemony of Hansen (as linked @501 had you cared to read that comment). Her it is - LINK. Nowhere does Hansen ever report to that 1988 Senate Committee, either in writing or verbally, that there was an average global temperature of "59 degrees Fahrenheit". Nowhere! That part of the newspaper report was incorrectly inserted into the account by the newspaper.
So that particular tree was rotten to the core. All the other "trees" are just as unreliable. If you like, we can address them tree-by-tree, but that would require you to actually read the comments people are responding to you with, to read and take on board what they are saying. But so far down this thread I see no sign of you doing that. So my advice here will likely fall on deaf ears.
MA Rodger, that's not a transcript from that session. Note how it does not include the question and answer part. Already informed you of this once, btw.
The fact we see Hansen and Jones and others quoted by media in the years 1988-1991 or 1992 all using 59 degrees as the mean lends credence to the NYTs quote you diagree with being valid and not a misquote. The mean of 59 degrees in Hansen's 1988 paper does the same.
[DB] Inflammatory and sloganeering snipped.
[JH] You are also skating on the thin ice of excessive repetition which is prohibited by the SkS Comments Poilicy.
randman @512,
You are entirely incorrect to state of the link I provided @501 and again @511 "that's not a transcript from that session." It is indeed a transcript. It is however not a transcript of the complete session. Being so, you are correct that it does not include the "question and answer part" of the session but if it had, my comment would have remained the same "Nowhere does Hansen ever report to that 1988 Senate Committee, either in writing or verbally, that there was an average global temperature of '59 degrees Fahrenheit'. Nowhere!" Perhaps you would care to check this by examining the transcript of the full session (which rather inconvenietly is somewhat longer than the part-transcript previously linked containing the relevant bit of Hansen's testiment.) This particular 'tree' within your 'forest' of unreliable quotes is as worthless in establishing your bold assertions as all the other 'trees'. I recommend you re-visit my comment @501 and consider each point in turn rather than ignoring them. Do note that the last does present irrefutable evidence which does actually make a complete nonsense of the bold assertions you have been making down this thread. (I even added a trace from Hansen et al (1981), just in case you start-up insisting that your 'randman event' was enacted on global temperature records prior to 1987.)
THe NYTs said he told Congress 59 degrees was the mean for the years between 1950-1980. Other media reported he claimed that as well, and in 1992, media reported Jones said the same thing.
And in 1981 in Hansen's paper, the mean he used for those years was roughly 59 degrees.
So far you've provided no facts or sources to counter this except your own incredulity. Where are your sources? I have provided mine.
[JH] Excessive repetiton and false claims snipped.
Either respond specifically to MA Rodger's #513 post or cease posting on this topic.
Let us stick with your ill-advised assertion that in June 1988 Hansen "told Congress 59 degrees was the mean for the years between 1950-1980." Let us deal with one-tree-at-a-time in your little forest of dodgy quotes.
In that regard, @514 you claim of me and my rebutal: "So far you've provided no facts or sources to counter this except your own incredulity." Are you having a laugh? @512 you dismissed the documentation provided @501/511 by insisting the Q&As at that 1988 Senate Hearing were missing but required (when they are not required) any insisting this missing aspect of the Senate Hearing had already been highlighted by you (although I see no evidence of such prior comment up-thread). And now you attempt to ignore the link I provide to the full documentation @513 (complete with Q&As). What is your problem? Can you not see that link? Because I'm sure everybody else can!!
MA Rodger at 19:50 PM on 2 October, 2017
The recent discourse about absolute global temperature appears to have ground to a halt but one aspect of this remained unmentioned and it might be appropriate to introduce it now - the Berkeley Earth temperature analysis. I was mindful that BEST would overly-complicate things for that enquirer. Yet as Rohde et al (2013) says "The Berkeley Average analysis process is somewhat unique in that it produces a global climatology and estimate of the global mean temperature as part of its natural operations." Thus mean absolute temperatures are to hand from the BEST data.
As a result, not only does BEST graph its global land temperature record using absolute values, it also provides within the data the absolute mean value of the anomaly base used (1951-80) for individual months and annually, the annual value being +8.7ºC. But this isn't entirely the end of this story.
Regarding the Land Only record, Rohde et al state "The global land average from 1900 to 2000 is 9.35 ± 1.45°C, broadly consistent with the estimate of 8.5°C provided by Peterson (et al 2011)." So the +8.7ºC value in the BEST data is a little different in Rohde et al. Further, this 8.5°C Peterson et al value is only re-quoted by Peterson et al, the value being taken from an NOAA FAQ table (on the 'mean temperature estimates' page), itself based on New et al (1999). Yet the true Global Land average temperatures are far far more dependent on local factors than the anomalies are. (Consider altitude - the average land altitude is 840m thus some 5ºC cooler than a sea-level average would be).
Note that while there are two different anomaly base periods in play here, the difference between them is tiny. The 1901-2000 mean is cooler than the 1951-80 mean by just 0.024°C in NOAA, with an almost identical tiny difference in BEST Land (and also BEST Land&Ocean).
Yet, while BEST Land temperatures may produce a global land absolute mean temperature "as part of its natural operations," that is not so clear with its Ocean data.
When combined with its Land Temperatures to create a full global Land&Ocean temperature series, BEST still provide the absolute value of the anomaly base (1951-80) within the data, that value being +14.720ºC or +15.305ºC (dependent on treatment of sea ice). Sea ice aside, the derevaton of an absolute value for SST is mostly trivial compared with the Land exercise. So if the quoted Land anomaly value of BEST & NOAA land temperatures is very close (+8.7ºC and +8.5ºC respectively) why are the global Land&Ocean values so different (+14.7ºC/15.3ºC and +13.9ºC respectively)? (And without an answer, this may have seen our recent enquirer running away shouting "I told you so!")
The SST data used by BEST is HadSST3 but the documentation on BEST's use of HadSST3 appears a little sparce. HadCRUT4 also uses HasSST3 but their average global mean anomaly value is roughly the same as NASA/NOAA and lower than BEST (although note the source of this HadCRUT4 data similarly give a BEST Land value as +9.17ºC).
So no answer is apparent to me. Yet, whatever its cause, the discrepancy makes not a jot of difference to the anomalies in the various SAT/SST records which are unaffected by anomaly base values and provide global temperature records that are pretty-much peas in a pod.
Oriolus Traillii at 22:54 PM on 8 November, 2017
Link http://www.globalwarmingart.com/wiki/Image:Satellite_Temperatures.png is broken (see "other lines of evidence for rising temperatures", bullet point 3 under "intermediate")
[DB] Fixed; thanks! (I also fixed the missing video on that page)
WesIsh at 01:07 AM on 15 February, 2019
How is it possible to measure the current temperature of Earth i.e. the biosphere with the precision and accuracy of 0.01 C over a time period of 1 year?
Max or not at 03:09 AM on 15 February, 2019
It ks not : https://www.ncdc.noaa.gov/sotc/global/201813
[PS] Link fixed. Please learn how to create links yourself by using the link button in the comments editor.
And to go straight to the chase, the link reports global land/sea surface temperature anomaly is estimated to +/- 0.15C not 0.01.